US3739054A - Process for the production of high shrinkage threads yarns and fibersfrom acrylonitrile polymers - Google Patents

Abstract

THIS INVENTION RELATES TO A PROCESS FOR THE PRODUCTION OF HIGH SHRINKAGE THREADS, YARN AND FIBERS FROM ACRYLONITRILE POLYMERS OF COPOLYMERS CONTAINING AT LEAST 50% BY WEIGHT OF POLYMERIZED ACRYLONITRILE AND MIXTURES THEREOF, WHEREIN THE THREAD OR YARN PRODUCED BY THE DRY SPINNING PROCESS IS EXPOSED TO ELEVATED TEMPERATURES IN THE PRESENCE OF STREAM AND IS THEN STRECHED AND DRIED. THE SPUN THREAD OR YARN OBTAINED BY THE DRY SPINNING PROCESS MAY BE CONTECTED WITH SATURATED STREAM UNDER PRESSURE.

Description

United States Patent US. Cl. 269-20 5 Claims ABSTRACT OF THE DISCLOSURE This invention relates to a process for the production of high shrinkage threads, yarn and fibers from acrylonitrile polymers or copolymers containing at least 50% by weight of polymerised acrylonitrile and mixtures thereof, wherein the thread or yarn produced by the dry spinning process is exposed to elevated temperatures in the presence of steam and is then stretched and dried. The spun thread or yarn obtained by the dry spinning process may be contacted with saturated steam under pressure.

This is a continuation of SN. 755,797, filed Aug. 28, 1968 and now abandoned.

The invention relates to a process for the production of high shrinkage threads, yarn and fibers from acrylonitrile polymers or copolymers and mixtures thereof by heat treatment of the polymeric material produced which has been dry spun.

Shrinkable fibers are of special interest for the production of high bulk yarn and pile fabric having different pile thicknesses. In this process shrunk fibers are usually worked up in admixture With a certain proportion of shrinkable fibres and the spun yarn or pile fabric is contacted with hot water at about 100 C. The shrinkable fiber portion is shrunk in this treatment, so the result that the pie-shrunk fibers of a yarn form undulations and curves, a high bulk yarn is produced. When pile fabric is subjected to the same hot Water treatment on the other hand, a finished product having different pile thicknesses is obtained.

The bulkiness of a yarn and the differences in pile thickness of pile fabric can therefore largely be adjusted by the amount of shrinkage the shrinkable fibers used undergo.

It is also known that shrinkable fibers of suflicient strength and elongaton can be produced from certain acrylonitrile copolymers by subjecting the spinning bands obtained by the dry spinning process to relatively slight stretching, for example to 180 to 250% of the initial length, and cutting the thread bundle up into staple fibers. The maximum shrinkage which these fibers undergo on boiling is 35 to 38%. By working up these fibers alone, yarn which has a maximum boiling shrinkage of 38 to 41% can be obtained as a result of spinning the yarn right to the end. The shrinkage values obtainable on boiling fibers and yarns in this way are, however, still insuflicient for some purposes.

A process for the production of high shrinkage threads, yarn and fibers from acrylonitrile polymers or copolymers containing at least 50% by weight, and preferably at least 85% by weight, of polymerized acrylontrile, together with other monomers compatible therewith have now been found which is characterized in that thread or yarn obtained by the dry spinning process is exposed to temperatures of 100 to 180 C. in the presence of steam and is then stretched at temperatures below 100 C. and dried.

The acrylonitrile polymers and copolymers containing at least 50% by weight, and preferably at least 85% by Patented June 12, 1973 weight, of polymerised acrylontrile which can be used in the production of the spun threads are already known in the art of synthetic thread and fiber production. Polymers of this type are obtained by copolymerization of acrylonitrile with one or more copolymerizable monoolefinically unsaturated monomers. Suitable monoolefinically unsaturated monomers are, for example, methacrylonitrile, vinyl chloride, vinylidene chloride, vinyl bromide, styrene, umethylstyrene or the esters of unsaturated carboxylic acids such as acrylic acid esters and methacrylic acid esters. Vinyl esters such as vinyl acetate, the amides of monoolefinically unsaturated carboxylic acids, such as acrylic acid amide and methacrylic acid amide, monoolefinically unsaturated carboxylic acids themselves such as acrylic acid and methacrylic acid, and other monoolefinically unsaturated compounds which contain acidic or basic groups, such as vinyl sulphonic acid, styrene sulphonic acid, inmethacryloylaminodiphenyldisulphimide, methacrylic acid N,N-dimetl1ylhydrazide or vinyl pyridines may also be used. The choice of comonomers is not critical in the practice of the process according to the invention. Any monoolefinically unsaturated compound which can be copolymerized with acrylontrile may be used.

It is unimportant in the production of the threads and yarn by the dry spinning process whether the polymers are produced by the process of precipitation polymerization and are then dissolved in a suitable organic solvent for spinning, or whether polymerization of the monomer mixture is carried out in such a solvent itself. Inorganic and/ or organic pigments such as titanium dioxide or color pigments or soluble additives may be incorporated in the acrylonitrile threads when spinning them without affecting the efficiency of the process of the invention.

When carrying out the discontinuous process according to the invention, the thread or yarn containing at least 15% by weight and preferably more than 40% by weight of water (based on the dry thread) are introduced in a freely shrinkable state into a chamber heated to to 180 C., preferably to to C. An atmosphere of steam is produced by evaporation of the water, which atmosphere in conjunction with the ambient temperature causes shrinkage of the spinning material. After termination of the shrinkage process, the thread or yarn is cooled and subjected, at a temperature below 100 C., to the after-treatment process which is described in greater detail below.

The shrinking of the individual threads only takes a few seconds, depending on the selected temperature. In order to carry out the shrinkage step, however, the period of resistance of the spinning material in the shrinkage chamber may vary from a few seconds to several minutes, depending on the amount of water in the spun material and the temperature in the chamber. A longer residence period for the shrunk material at elevated temperaturs should, however, be avoided because otherwise the color of the unbleached and undyed threads is adversely affected.

When carrying out the process discontinuously and in particular when treating larger quantities of spun material containing little or no water, saturated steam under an absolute pressure of at least 1.1 kg. wt./cm. and preferably 1.5 to 4.0 kg. wt./cm. may be used in a pressure chamber to adjust the steam atmosphere and temperature. The spun thread or yarn is deposited for this purpose free of tension, under conditions in which it is free to shrink, in perforated metal containers which are inserted in the pressure chamber. The saturated steam is then introduced at the desired pressure into the pressure chamber which may if desired previously have been evacuated. After termination of the shrinking step, the chamber is briefly opened to relieve pressure and may be evacuated, when partial drying and cooling of the shrunk spun material occurs. The shrinking step may be completed by briefly repeating the saturated steam treatment in the pressure chamber followed by relief of pressure several times.

When carrying out the process according to the invention continuously, apparatus heated to 100 to 180 C., preferably 110 to 160 C. is preferably used. The apparatus may contain, as transport elements, drum sieves or rollers having different speeds of rotation or belts, which ensure free shrinkage of the transported spun threads or yarn when the process is carried out continuously. The water content of the spun material introduced should again be at least 15% by weight and preferably more than 40% by weight, based on the weight of thread. Spinning material containing little or no water may, of course, also be worked up in the present invention. In such as case, care should be taken to ensure the steam atmosphere, which is absolutely essential during the shrinking step, is maintained by introducing steam into the heated apparatus. There are thus two possible methods of steam treating material obtained by the dry spinning process within the given temperature range according to the invention:

(1) Dry heat treatment of wet spun material (2) Hot steam treatment of dry or only moist spun material.

Shrinking of the spun thread or yarn can also be carried out by a combination of the discontinuous and the continuous mode of operation.

When producing the high shrinkage thread, yarn and fiber, the spun material which has been shrunk as described above is then stretched to 180 to 320% of its initial length in a water bath at temperatures below 100 C., preferably at 65 to 95 C., after having been dressed with an antistatic preparation, and is dried in a heated apparatus. The drying temperature should be of the same order as the stretching temperature in all the operations following the stretching process. In order to produce fibers, the yarn is crimped and cut up to the desired staple length.

Thead, yarn and fiber produced in this way have, on average, 10 to 25% higher boiling shrinkage than when the spun material has been treated under known conditions and/ or when after treatment is carried out above 100 C. Fiber which have a boiling shrinkage of about 50% can therefore be easily produced.

The boiling shrinkage K is determined by treating an individual thread or thin yarn of initial length 1 (in practice measured under a pre-tension of 0.01 to 0.02 g./ den.) for 5 minutes without tension with hot water at 98 to 100 C., and then chilling in a water bath of about 20 C. The length 1;; is then determined under the same pretension after 30 minutes on the shrunk thread or yarn which has been stored free of tension. The boiling shrinkage K is then calculated as a percentage according to the equation:

1 1 K%= 111A K EXAMPLE 1 A copolymer of 94% by weight of acrylonitrile, 5.5% by weight of methyl acrylate and 0.5% by weight of mmethacryloylamino diphenyldisulphimide of K-value 84.5 1 is spun by the dry spinning process from a 26.5% by weight dimethylformamide solution at a draw-off speed of 338/m./min. to form a yarn of 14,000 individual threads of titre 8.5 den. This yarn which contains 16.4% of dimethylformamide is placed, free of tension, in 5 kg. portions in a perforated metal container which is then placed in a pressure chamber. The pressure chamber around which hot water circulates is evacuated. Immediately thereafter, saturated steam is introduced into the pressure chamber for 3 minutes, so that the temperatures indicated in Table 1 are achieved. The spun yarn which shrinks in this step is partly dried by the subsequent evacuation of the pressure chamber, and is cooled below C.

The steam treated spun yarn is then stretched continuously at 75 C. to 220% of its intial length in a water bath which is 5 m. in length, and the yarn is then washed with Water at 50 C., dressed with an antistatic dressing and dried in a drying drum at 65 to 70 C. To produce the fibers, the stretched yarn is subjected to compression crimping and cut up into fibers mm. in length.

Details of the absolute steam pressure employed, the temperature, shrinkage of the spun yarn, boiling shrinkage of the fibers according to the invention and their moisture content are shown in Table 1.

The boiling shrinkage of a fiber of a spun material which has not been shrunk, but which has been aftertreated in the same manner is indicated under Example If which is a comparative example.

TABLE I Determined according to Fikentscher, Gellulosechemie 13, 58 (1932) Experiment number 1a 1b 1c 1d to It Absolute pressure of the steam in the pressure chamber (kg.

wt./em. 1.5 1.9 2.3 2.5 8.0 Temperature in the pressure chamber C.) 110 118 124 129 133 Shrinkage of the spun yarn in the pressure chamber (percent) 10.7 12.7 13.8 14.0 14.2 Boiling shrinkage of the fiber (percent) 48.0 48.3 50.5 51.0 52.0 35.0 Moisture content of the shrunk fiber (percent) 8.4 7.7 8.3 8.1 7.4 8.6

1 Comparison.

EMMPLE 2 The spun yarn described in Example 1, comprising 1400 individual threads of titre 8.5 den., is passed continuously through a water bath at a temperature of 50 C. and is squeezed off between a pair of rollers so that the water content, based on the polymer, is 60 to 65%. The spun yarn is then conveyed free of tension on an endless band through a heating cupboard at 135 to C. The spun yarn shrinks by 10% in the process.

The shrunk yarn is then stretched to 220% of its initial length in water at 75 C., and is then washed with water at 50 C., dressed with an antistatic dressing and dried at 65 to 70 C. The endless yarn is crimped in a compression crimpage chamber at 50 C. and cut up into fibers of staple length 120 mm.

In a comparative test, a spun yarn which has not been shrunk in after-treated in the same manner.

In order to test the suitability of the fibers for use in high bulk yarn, a yarn of Nm. 24/1 and T/m. 3202 is completely spun and the shrinkage of the yarn on boiling is determined. When all the yarn is spun, the shrinkage of the yarn on boiling is always slightly higher than the shrinkage on boiling of the fiber put into the process.

5 EXAMPLE 3 A 22.5% by weight solution in dimethylformamide of a 100% acrylonitrile polymer (K-value 89) containing 0.5% titanium dioxide (based on the polymer) is spun by the dry spinning porcess, at a draw-off rate of 300 m./min. to form a yarn containing 3600 individual threads of titre 11.6 den. The yarn is carried continuously through a water bath at 45 C. and is squeezed by means of rollers to a moisture content of 50 to 55%, based on the polymer. The yarn is then passed through a heating cupboard at 140 to 145 C. under conditions of free shrinkage for 3 minutes. The yarn shrinks by 12% in this step.

The shrunk yarn is stretched in a water bath at difierent temperatures and different stretching ratios, is dressed with an antistatic dressing, and is dried at 65 to 70 C. The temperature of the stretching vat, the stretching ratio and the shrinkage of the yarn on boiling are entered in Table III.

In a comparative test, an untreated yarn is heat treated at 85 C. under the same conditions of stretching and drying.

TABLE III Shrinkage on boiling, percent Conventionally Spun thread shrunk, and after-treated after-treated according spun thread to the invention (comparison) Stretching temperature..- 75 C. 85 C. 85 C.

EXAMPLE 4 A solution of a copolymer of 63% by weight of acrylonitrile, 35% by weight of vinylidene chloride and 2% 0f m-methacryloylamino diphenyldisulphimide in dimethylformamide (solids content of the solution 35% by weight) is spun by the drying spinning process at a drawolf rate of 360 m./min. to form a yarn containing 5600 individual threads of titre 8.5 den. Portions of 5 kg. of this spun yarn which contains 14.8% by weight of dimethylformamide are deposited free of tension in a perforated metal container. The spun material in the metal containers is twice contacted with saturated steam at a pressure of 2 kg. wt./cn:l. absolute for 3 minutes at an interval of 5 minutes, in a pressure chamber. The spun yarn which shrinks by 5.7% is dried by subsequent evacuation of the pressure chamber and is cooled below 100 C.

Samples of the steam treated yarn are continuously stretched to 190 and 220%, respectively, of their initial length, at 75 C. in a water bath, and are subsequently washed with Water at 50 C., dressed with an antistatic dressing, and dried at 65 to 70 C.

Stretching, shrinking on boiling of the threads produced according to the invention, and their moisture content are summarized in Table IV. Results of comparative experiments carried out with conventionally produced shrinkage threads are also given.

TABLE IV Spun thread bundle Convention-ally shrunk and afterafter-treated treated according spun thread bunto the invention dle (comparison) Stretching to of the clillgbsolute pressure of the steam in the pressure chamber=2 Kg. wt./

We claim:

1. A process for the production of high shrinkage fiber from acrylonitrile polymers, copolymers of acrylonitrile and one or more copolymerizable monolefinically unsaturated monomers, or mixtures thereof consisting essentially of (1) drying spinning said polymer, copolymer or mixture thereof;

(2) heating the fiber obtained by dry spinning said polymer, copolymer or mixture thereof, to a temperature of 100 C. to 180 C. in the presence of saturated steam at a pressure of 1.5 to 4.0 kg. wt./cm. with the fiber in a freely shrinkable state; then (3) stretching the fiber 180% to 320% of its initial length at a temperature below 100 C.; and then (4) drying the stretched fiber at a temperature below 2. The process of claim 1 wherein said heating step (2) is conducted at a temperature of C. to C.

3. The process of claim 1 wherein said stretching step (3) is conducted at a temperature of 65 C. to 95 C.

4. The process of claim 1 wherein said stretching step (3) is conducted in water.

5. The process of claim 1 in which a shrinkage of at least 5.7% is effected in said fiber during the step (2) of steam treatment.

References Cited UNITED STATES PATENTS 2,768,868 10/1956 Hewett et al 8130.1 2,920,934 1/1960 Schaefer et a1. 8130.l 3,097,415 6/1963 Davis 264206 2,761,754 9/1956 Jones et a1. 264182 2,984,912 5/1961 Robertson et a1 264182 3,164,650 l/1965 Kocay et a1 264206 3,397,426 8/1968 Fujita et al. 264210 FOREIGN PATENTS 875,052 8/ 1961 Great Britain 269-182 7,898 4/1966 Japan 264206 JAY H. WOO, Primary Examiner U.S. C1. X.R. 264210 F, 234

UNITED STATES PATENT owner CERWWCA'EE 0F QWRREQTWN Patent No. 3, 739 054 Dated 12 June 1973 SON. In Horst Wieden; Alfred Nogaj'; Herbert Ma'rzolph It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

COLUMN LINE ERROR l 5 "Noga" should be Nogaj and "Morzolph" should be Marzolph 4 46 I I "1400" should be 14000 0 4 60 v shrunk in" should be shrunk is 6 21 w "drying" should be dry 6 I 53 v I "2691182" should'be 264-182 signed and sealed this 25th day of Dec ember- 1973.

(SEAL) Attest:

EDWARD M. FLETCHERJR; RENE Do 'IEGTMEYER Attesting Officer Acting Commissioner" of Patents FORM po'wso 7 USCOMM-DC 6O376-P69 a U.S. GOVERNMENT PRINTING OFFICE: I959 0-366-334